Project

Two component systems in Streptococcus suis: what is the role of SSU0827/8 and SSU1930/1 in virulence?

Background and aim

Streptococcus suis is one of the major porcine pathogens worldwide. It is also considered an important zoonotic pathogen that can be transmitted from pigs to human. Some strains highly resistant to antibiotics have been isolated both from pigs and humans.
Despite its relevance, relatively little is known about the mechanisms employed by S. suis to infect its host. The main method of disease control has been through use of antibiotics, but emerging resistance is a growing problem. There is a need for alternative treatment. Bacterial two-component systems (TCSs) are a way of sensing changes in the environment, e.g. during host invasion, and thus are important during S. suis infection. Through expression data analysis, we have previously identified two candidate TCSs, encoded by the genes SSU0827 and SSU0828, SSU1930 and SSU1931 respectively, that are likely to be involved in the infection process. In order to assess the precise function of these candidate TCSs, we created mutants with these TCS genes knocked out. The results of experiments done in our lab indicate that both the SSU0827/28 and SSU1930/31 TCSs are directly or indirectly involved in growth rates, transformation efficiency, antimicrobial peptide tolerance and acid tolerance.

Techniques and procedures you will get acquainted with:  

In order to better characterize the role and the function of these TCSs the student will perform several in vitro experiments, including the differential survival of mutant and wild type strains in the phagosomes of human and pig neutrophils, mouse macrophages and adhesion invasion assays with human and pig cell lines. The student would also perform additional in vitro experiments including antimicrobial peptide assays and  hydrogen peroxide exposure assays and in vivo infection studies using zebrafish embryos.
The student could also participate in the construction and characterization of other TCSs mutants.
For this purpose, the student will gain insight into pathology of important bacterial pathogens, and will become acquainted with useful molecular biology techniques such as PCR, SOEing PCR, general cloning techniques, adhesion and invasion assays, and in vivo and in vitro infection experiments.